Napster co-founder and former Facebook president Sean Parker has joined micro-blogging site Twitter and apologised to Mark Zuckerberg for signing up to the rival website.

Sean Parker has joined Facebook rival Twitter (Pic: Twitter)

Parker joined Twitter on Monday with the username @sparker. He has so far only posted one message, a short apology to Zuckerberg.

The Spotify investor wrote: âSorry Zuck, I had to do it eventually. (Actually @scooterbraun made me do it.)â

@scooterbraun is Scooter Braun, Justin Bieberâs manager.

Parker has clearly been planning his arrival on Twitter for some time as his account was immediately verified once it was set-up. At the time of writing, the co-founder of Napster had already acquired over 20,000 followers.

The 31-year-old made headline last month for his lavish party to celebrate Spotifyâs new partnership with Facebook. Parker is reported to have invested between $15million and $30million in the Swedish company and was instrumental in bringing the music-streaming site to the US.

The entrepreneur, who was memorably depicted by Justin Timberlake in David Fincherâs Oscar-winning film The Social Network, recently graced the front cover of Forbes magazine. In its annual rich list, Parker was valued by the magazine at $2.1billion.